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There is a bug in the function nilfs_segctor_collect, which results in
active data being written to a segment, that is marked as clean. It is
possible, that this segment is selected for a later segment
construction, whereby the old data is overwritten.
The problem shows itself with the following kernel log message:
nilfs_sufile_do_cancel_free: segment 6533 must be clean
Usually a few hours later the file system gets corrupted:
NILFS: bad btree node (blocknr=8748107): level = 0, flags = 0x0, nchildren = 0
NILFS error (device sdc1): nilfs_bmap_last_key: broken bmap (inode number=114660)
The issue can be reproduced with a file system that is nearly full and
with the cleaner running, while some IO intensive task is running.
Although it is quite hard to reproduce.
This is what happens:
1. The cleaner starts the segment construction
2. nilfs_segctor_collect is called
3. sc_stage is on NILFS_ST_SUFILE and segments are freed
4. sc_stage is on NILFS_ST_DAT current segment is full
5. nilfs_segctor_extend_segments is called, which
allocates a new segment
6. The new segment is one of the segments freed in step 3
7. nilfs_sufile_cancel_freev is called and produces an error message
8. Loop around and the collection starts again
9. sc_stage is on NILFS_ST_SUFILE and segments are freed
including the newly allocated segment, which will contain active
data and can be allocated at a later time
10. A few hours later another segment construction allocates the
segment and causes file system corruption
This can be prevented by simply reordering the statements. If
nilfs_sufile_cancel_freev is called before nilfs_segctor_extend_segments
the freed segments are marked as dirty and cannot be allocated any more.
Signed-off-by: Andreas Rohner <andreas.rohner@gmx.net>
Reviewed-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Andreas Rohner <andreas.rohner@gmx.net>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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| .. | ||
| alloc.c | ||
| alloc.h | ||
| bmap.c | ||
| bmap.h | ||
| btnode.c | ||
| btnode.h | ||
| btree.c | ||
| btree.h | ||
| cpfile.c | ||
| cpfile.h | ||
| dat.c | ||
| dat.h | ||
| dir.c | ||
| direct.c | ||
| direct.h | ||
| export.h | ||
| file.c | ||
| gcinode.c | ||
| ifile.c | ||
| ifile.h | ||
| inode.c | ||
| ioctl.c | ||
| Kconfig | ||
| Makefile | ||
| mdt.c | ||
| mdt.h | ||
| namei.c | ||
| nilfs.h | ||
| page.c | ||
| page.h | ||
| recovery.c | ||
| segbuf.c | ||
| segbuf.h | ||
| segment.c | ||
| segment.h | ||
| sufile.c | ||
| sufile.h | ||
| super.c | ||
| the_nilfs.c | ||
| the_nilfs.h | ||